Data released yesterday by Zoopla shows that OnTheMarket has “got off to a slow start”, said the portal.

Zoopla also said its own traffic has been unaffected by the launch of OTM and that it had more hits in a single day than OTM had over the whole of February.

It accused OTM of “cannibalising” traffic from its own members’ websites.

Zoopla said that OTM is proving “a very expensive proposition” for its member agents.

However, OTM hit back strongly, last night saying once again that the figures were “wildly inaccurate” and that Zoopla’s listings had almost halved in six months, reducing from 1.1m last September to 630,000 by the end of February.

OTM also said that “over the longer term” it aims to reduce portal fees for agents.

Zoopla’s full release says: “With over a month and a half under its belt and its multi-million pound marketing campaign in full swing with over 3,000 TV ads aired in February alone, the latest independent data from Hitwise confirms that OnTheMarket.com has got off to a slow start with consumers, despite the significant marketing spend and heavy branding by member agents.

“According to February’s full month figures from Hitwise, daily visits to OTM averaged under 38k per day compared with over 1.25 million per day for Zoopla Property Group (ZPG) and 2.4 million per day for Rightmove (RMV).

“OTM’s audience size in February was less than 3% of Zoopla’s and only 1.5% of Rightmove’s and the market share for each of the portals as a percentage of all UK property internet traffic was 0.63% for OTM versus 21.3% for Zoopla and 40% for Rightmove.

“And the latest data for March also shows that ZPG’s audience has so far been unaffected by the launch of OTM and actually experienced record traffic last Monday with more visits in a single day than OTM’s total visits for the entire month of February, according to Hitwise.

“These figures highlight that OTM is currently a very expensive proposition for its members and even more so with the requirement to give up a huge audience by dropping either ZPG or RMV.

“And it is also clear from the data that much of the search traffic to OTM so far is coming at the expense of cannibalizing the traffic to its members’ own websites.

“Lawrence Hall of ZPG said: ‘OTM members are today paying 30 to 40 times more than they should be for their digital marketing whilst offering substantially less exposure to their clients, so they are being disadvantaged both competitively and financially.

“Portals are no different from any other marketing channel that must deliver an audience to its advertisers and charge accordingly. If OTM was charging based on their audience, building traffic fast might be a less urgent priority.

“However, given that they are charging today on a promise for tomorrow, it is hard to see how sustainable it is to continue to force their members to spend more and get far less, effectively achieving the exact opposite of their stated aim of improving the portal value proposition.’”

The full OTM response quotes chief executive Ian Springett and says: “The figures being quoted by Zoopla Property Group with regard to traffic levels at OnTheMarket.com are wildly inaccurate.

“We stand by every figure we have previously stated and there is no question that less than six weeks after our launch, on March 6 and 7, we passed the mark of two million unique visitors to the website. We reiterate that we are confident in becoming the number two portal within a year.

“It is unsurprising that Zoopla has chosen to distribute these figures following the heavy losses it has suffered as a result of our presence in the portals market. We have more than 4,800 contracted offices; around 90% have chosen to leave Zoopla/PrimeLocation.

“In September, Zoopla was claiming on its website to have more than 1.1m houses and flats for sale and to rent across the UK. Searching properties for sale and to rent in England, Wales and Scotland on Zoopla shows that this number has reduced to just over 630,000 as at 27th February.

“The latest inaccurate traffic figures are nothing more than a weak attempt by Zoopla to intimidate agents who have chosen to remove all of their properties and their corresponding advertising expenditure from them to list with OnTheMarket.com

“We have also been told by many member agents that having removed their properties from their less effective portal, it has become obvious just how many leads were previously duplicated, and leaving Zoopla has had no impact on their business. It was and continues to be the choice of our member agents to decide from which portal to remove their listings.

“Many have joined OnTheMarket.com because it provides a better environment in which to bring their clients’ properties to market, without the unhelpful and potentially misleading additional information included by Zoopla on its full details pages nor the intrusive advertising for unrelated products and services which can distract users from the property being advertised.

“Ultimately, the property-seeking public and the agents themselves will decide over time which portals deliver the most value.

“It is over the longer term that OnTheMarket.com aims to reduce portal fees for agents. By restraining and eventually reversing the current rise in fees, this will create more potential headroom for agents to compete more effectively, whether on price or service quality, which will benefit their clients and the property-seeking public in the long term.”